SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e246ff84cd0ac126f86cc4b6de0570d6ee042e636ff9b1377ead1d3e212572d2' 
  AND token = 'dIUksDn8+r9nVjygh2xmtjeKlnzFpoX0UnwSyYjSVVI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}